glossary

8rd thread: Refers to a thread with a rounded “V” profile that contains 8 threads per inch.

10rd thread: Refers to a thread with a rounded “V” profile that contains 10 threads per inch.

Acid Service: The process of running acid through a well in order to accomplish one of many services, such as the cleansing of excess drill “mud” out of the well (mud service), dissolving rocks or remedial repair of the well.

Aluminum killed: The process by which aluminum is added to molten steel in order to chemically remove excess oxygen from the steel to such a level that no reaction occurs between oxygen and carbon during solidification.

Ambient: A term usually used to describe the surrounding temperature or environment.

Anode: The electrode where electrons leave an operating system. In the process of cathodic shielding, the anode takes the role of the sacrificial cell to the attacking cathode. The anode is the electrode where oxidation occurs.

Annular fluid: The fluid contained in the space between producing tubing and well casing. This fluid can be of varying composition.

API: The acronym for the American Petroleum Institute. This organization’s major function is to provide services to the oil and gas exploration, production, and processing industries. API publishes and controls the development and revision of standards used for the production of products used in the above industries.

Axial load: A load which is applied along the central axis of a load bearing structure, such as a drill string or casing or tubing string.

Austenite: A microstructure with a solid solution of one or more elements in face-centered cubic iron (gamma iron). Unless otherwise designated, the solute is generally assumed to be carbon.

B/L (Bill of Lading): A legal document that must accompany the means of shipping (truck, railroad, barge, etc.) a product. The bill of lading is a signed statement that documents what and how much s being loaded on that shipment.

Break-out: The process of loosening a threaded connection, such as a drill, casing, or tubing string.

Brine: A solution of sodium chloride (salt) and water often encountered in the wellbore of wells.

BTC (Buttress Thread and Coupled): A thread type used on casing and tubing which derives its name from the thread profile. The buttress thread provides a higher thread strength than 8 round threads.

Buckling: A term used to describe the permanent mechanical deformation that results when a slender column, such as tubing or casing string, is overloaded in compression. The compressive load which causes the buckling is often produced by the weight of the string of casing or tubing.

Bundling: The process of securing multiple joints of pipe or tubing with steel bands to facilitate the ease of handling. Typically, there are industry standards determining the number of pieces in, and the shape of, a bundle. This is based upon OD and weight per foot.

Buttweld Pipe: See Continuous Pipe Weld.

Carbon dioxide: See CO2

Cathode: The electrode where electrons enter an operating system. In the process of cathodic shielding, the cathode takes the role of the attacking cell to the sacrificial anode.

Cathodic shielding: Partial or complete protection of a metal from corrosion by making it a cathode using either a galvanic or an impressed current.

Cementing: A well completion operation in which slurry of cement is pumped down through the casing bore and up between the outer surface of the casing and the well bore. The cement seals and secures the casing in position after it is allowed to cure.

Cementite: A compound of iron and carbon, known chemically as iron carbide, having the approximate chemical formula Fe3C.

CO2: The chemical symbol for carbon dioxide gas which is commonly found in oil and gas wells. This gas, when combined with water, produces a corrosive solution of water and carbonic acid that can cause severe pitting corrosion in tubing and casing. Corrosion caused by CO2 is known as “sweet corrosion”.

Collapse Pressure: Pressured applied externally which is expected to cause permanent inward deformation in casing or tubing.

Collapse setting depth: A depth at which well and/or formation fluids are expected to produce an external pressure which can collapse pipe used in a particular completion application. Usually, the casing or tubing string is designed with a safety factor assuring that the pipe in the string is never subjected to the expected collapse pressure.

Collapse test inspection: Subjecting a section of pipe to an external pressure that causes the pipe section to deform plastically about its axial center line. Guidelines for collapse testing of oil country tubulars are provided in the American Petroleum Institute’s (API) publication, Bulletin 5C3

Continuous casting: A casting technique in which a cast shape is continuously withdrawn through the bottom of the mold as it solidifies, so that its length is not determined by mold dimensions. Tis process is used chiefly to produce semi-finished mill products such as billets, blooms, ingots, slabs, strip, and tubes.

Continuous Weld Pipe: In common usage, a phrase for continuous butt welds. Furnace-welded pipe produced in continuous lengths from coiled skelp and subsequently cut into individual lengths, having its longitudinal butt joint forge welded by mechanical pressure developed in rolling the hot-formed skelp through a series of round pass welding rolls.

Crush Test: A synonym for the flattering test required in the American Petroleum Institute (API) and the American Society for Testing and Materials (ASTM) pipe specifications. The flattening (crush) test is a destructive test used to verify the soundness and ductility of the longitudinal weld in welded pipe.

D/t ratio: The ratio of the outside diameter of pipe to its wall thickness. This ratio is often referred to when the collapse strength of pipe products is discussed. In general, the larger the D/t ratio for a particular diameter, the lower the collapse strength of the pipe.

Die Stamp: A steel stamp containing either an alpha or numeric character used to make a permanent identification mark in products such as casing, tubing, and couplings.

Drift test: A test wherein a mandrel of a minimum diameter and length is inserted into tubular goods to verify that the product’s inside diameter will allow the passage of downhole tools without becoming lodged inside the pipe.

Drillstring/casing interaction: The amplitude of vibrations transmitting from the drillstring to the casing while drilling.

Ductility: The ability of a material to deform plastically without fracturing.

Elastic range of collapse: The collapse strength of a tubular product which has been calculated based upon the elastic modulus of the pipe material. (Refer to API Bulletin 5C3 for more information)

Electrostatic application: A process of paint or coating application where steel pipe is electrically charged so as to attract the paint or coating material. The process minimizes overspray and material waste.

Elongation: In tensile testing, the increase in the gage length, measured after fracture of the specimen within the gage length, usually expressed as a percentage of the original gage length.

EMI Inspection: An automated pipe inspection process wherein electro magnets are used to induce a magnetic field, either longitudinal or transverse, into the body of the pipe as it is conveyed through the magnetic inductor and sensors. Material imperfections disrupt the magnetic field and cause the flux lines of the magnetic field to enter the air space near imperfection in the pipe body. The inspection system contains sensor coils which detect the disruption of the magnetic field. The sensor coils send signals to an amplifier. The amplified signal is then sent to a computer which determines the location of the imperfection. The computer then sends a report to a printer and/or storage disk. The computer also controls a paint marking system which marks the pipe in the location of the detected imperfection.

End area inspection: An inspection designed to detect transverse and longitudinal defects found inside and outside surfaces of a pipe’s end areas including pins, couplings, threads, and upsets.

Engaged thread: Those threads that are mated and contribute to distributing the load carried by the threaded connection.

ERW (Electric Resistance Welded): See HF ERW

EUE (External Upset End): The acronym describing the end of a joint of pipe that has been upset to increase the outside diameter so that a thread can be cut on the end of the pipe.

Fatigue Failure: A mode of failure that is initiated by the application of a tensile or compressive load applied cyclically. Fatigue failures sometimes occur in the root of the last engaged thread of the wellhead tubing joint during downhole service activities.

FBN-AU (Full Body Normalized- After Upset): A heat treating operation wherein an item such as steel pipe is subjected to a normalizing heat treatment over the full length of the pipe. Normalizing consists of heating the pipe body until the steel structure transforms into the austenite phase (Approx. 1350 F). The pipe is then allowed to air cool to ambient temperature. The resultant micro structure is a combination of ferrite and pearlite.

Ferrite: A form of iron containing a maximum of 0.025 weight percent carbon.

Final Inspection: The inspection of the product after all processing has been performed on the pipe.

Flattening: A process which eliminates any existing curvature of flat strip during the preparation of the steel strip for forming.

Forming: The process of shaping a flat steel strip into pipe by passing the steel through a series of rolls in order to provide the desired OD and a perfectly round shape.

Full Body Normalized-After Upset: See FBN-AU.

Galling: A term used to describe the condition of threaded connection which has experienced mechanical damage during the makeup or the break-out of the connection. The term galling indicates that mating threads on the male and female components have mechanically bonded (welded) together at high spots on the threads due to friction. Galling of threads usually indicates that the threads were made-up without proper lubrication or too high a makeup speed.

Girth Weld: The circumferential weld joining two lengths of pipe. This term is used when describing the joining of line pipe to form a pipe line.

H2S: The chemical symbol for hydrogen sulfide gas. A noxious, poisonous gas often found dissolved in water in oil and gas wells. This gas is known to cause steel components to experience unexpected catastrophic failures. The gas causes steel in certain strength ranges and in certain heat treated conditions to become embrittled. The embrittlement is due to disassociation of hydrogen gas with the sulfur corrosion product iron sulfide. The small hydrogen atom is absorbed (diffuses) into the metal matrix and settles in the interstices (voids) between iron atoms. The atomic hydrogen then combines into molecular hydrogen. Molecular hydrogen occupies a higher volume than atomic hydrogen. This increased volume causes internal stress within the metal matrix. The increased stress causes the material to become embrittled.

Heat affected zoned: The material adjacent to the weld line in electric resistance welded (ERW) pipe that has been heated during the welding process to a temperature greater than or equal to the material’s transformation temperature. For steel, the transformation temperature is approximately 1350 F. This zone cab contain hard brittle structures and should be heat treated to produce a normalized microstructure if the pipe is not given either a full body normalized or quench and tempered heat treatment.

Heat Treat: The thermal processing of metallic materials to provide homogenous mechanical properties.

HF ERW (High Frequency Electric Resistance Weld): A welding process wherein fusion is affected by applying high frequency welding current to the surfaces joined at an energy level which causes the surfaces to melt. The molten surfaces are forged together affecting a weld through the application of side roll pressure. The resulting weld is known as an autogenous (without filler metal added) weld. The term high frequency indicates that the flow of electrical current around the welding seam changes direction at a frequency of 400,000 cycles per second (Hertz) or higher. Standard resistance welding uses welding current operating at 60 Hertz.

Hydrogen Sulfide: See H2S

Hydrostatic Test: A proof test wherein a vessel such as pipe is filled with water and then pressurized to a level intended to demonstrate the pressure tight integrity of the product.

ID: The abbreviation for the inside diameter of pipe. It can be calculated by subtracting the wall of pipe from the outside diameter (OD).

IJ: The abbreviation of the integral joint connection used for API tubing. The connection is made by upsetting the ends of tubing so that a male connection can be cut on one end of the pipe and female connection can be cut on the opposite end of the pipe. This connection eliminates the need for a coupling to join lengths of tubing to form a tubing string.

Joint Strength Round Threads: A term that describes the tensile loads that tubing or casing string can carry without experiencing separation when the threaded connection is made with an 8-thread or 10-thread per inch configuration. The thread profile is a “V” configuration. With tensile loads below the round thread joint strength, the threaded connection is not expected to experience fracturing of the threads or jump-out of the connection.

Jump-out: The separation of a threaded connect due to tensile overload of the connection. A connection that has experienced a jump-out separation is characterized by the upsetting of the inside diameter (ID) of the pipe beneath the threads.

Lamellar pearlite: A microstructure found in hot rolled or normalized steel products which consists of layers of ferrite and cemetite (iron carbide)

Last Engaged Thread: The last thread in a power tight connection that actually carries part of the load when the connection is placed in tension.

LTC (Long Thread and Coupled): This is the description of a threaded connection that has an API, 8-round, long thread.

Major Diameter: The crest diameter of the external thread and the root diameter of the internal threads. It is the largest diameter of the thread.

Makeup Loss: The amount of footage loss after the makeup of a string of casing and tubing.

Makeup: The processes of threading a male and female connection together either hand-tight or power-tight.

Martensite: A meta-stable phase of steel, formed by transformation of austenite below the Ms (or Ar) temperature. It is an interstitial supersaturated solid solution of carbon in iron having a body-centered tetragonal lattice. Its microstructure is characterized by an acicular or needle-like pattern.

Metallurgy: The art and science of extracting metals from their ores, refining them, and preparing them for use. The term can also be described as the technical details of a metal.

Microstructure: The Structure of a metallic material as revealed under microscopic examination. In order to examine the structure of metals, the surface of the metallic product has to be specially prepared to reveal it microstructure. Microstructures related to steel products include the following: (1) Ferrite- Low carbon iron; (2) Pearlite- Lamellar structure of  ferrite and cementite; (3) Austenite- Face-centered cubic form of iron above 1333 F; (4) Martensite- Body centered tetragonal form of iron.

Minimum Internal yield pressure: The internal pressure that is expected to cause permanent, plastic deformation of a casing tube string. The internal pressure can be applied by cementing or fracturing operations or by formation pressures.

Minimum Ultimate Strength (Ultimate Tensile Strength): The axial tensile stress at which a structure, such as a drill, casing, or tubing string is expected to experience failure. The stress is determined by dividing the load (expressed in pounds) carried in tension by the cross-sectional area (expressed in square inches) of the structure carrying the load. The stress is expressed in pounds per square inch (psi).

MTR (Material Test Report): This type of report provides the mechanical (tensile, yield, impact, and hardness) and chemistry test results for products such as casing and tubing.

Nominal: A term used to express the theoretical diameter or wall thickness of pipe. The actual diameter or wall thickness will vary within the accepted limits from the nominal value.
NUE (Non-upset End): A threaded tubing connection consisting of pin threads cut on both ends of a tube that has a nominal outside diameter (OD) and nominal wall thickness. One end of the tube will have a threaded pipe coupling made-up power-tight on it so that individual lengths of tubing can be joined together to form a tubing string.

OD: The abbreviation for the outside diameter of a pipe.

Optimum Torque: The theoretically ideal torque value required to assure proper makeup position of a string of pipe per API Bulletin 5C1.

Ovality Inspection: The dimensional inspection of the outside diameter of pipe to determine the difference in the maximum and minimum outside diameter. Pipe ovality is the difference.

Oxidation: The technical term used to describe corrosion. Oxidation indicates that oxygen has combined with an element such as iron to form an oxide (iron oxide), a corrosion product.

Packer: Instrument used in the sealing of a well in order to force oil and/or gas through the tubing.

Pearlite: A microstructure typically found in steel products that have been either hot rolled or normalized. The microstructure consists of lamellar (layered) ferrite and cementite.

Pigging: A process used in pipelines to perform duties such as cleansing, identifying holes, and checking weld integrity by driving a “pig” along the inside of the pipeline.

Pin threads: An oil country term used to describe the male end of a threaded connection.

Plastic range of collapse: The collapse strength of pipe which falls within the range calculated using the Plastic Collapse Pressure Formula specified in the American Petroleum Institute’s (API) Bulletin 5C3.

Potable (water): Water that is considered safe for human consumption.

Proprietary products: Products that have unique characteristics specific to a particular manufacturer. A unique characteristic can include properties such as collapse strength, yield strength, wall thickness, and special heat treatments.

Quench & tempered: A term used to describe the heat treating process whereby steel products, such as pipe, are heated to the austenitizing temperature approx (1600 F ) and then quenched (rapidly cooled) to ambient temperature. The product is then tempered (heated) at a lower temperature to improve the product’s ductility and to develop the required mechanical properties, such as yield strength, tensile strength, and hardness.

Ringworm corrosion: A term used to describe a circumferential band of corrosion which occurs on the inside surface of upset pipe that has not been full-body heat treated after upsetting. Corrosion occurs in the area of the upset-runout due to the difference in microstructure that exists in the upset and the upset-runout.

Rockwell Hardness Inspection: Test which produces a numerical value the expresses the resistance of a material to indentation with a small diamond point or a 1/16 inch diameter ball. This correlates directly with strength and is measured in psi.

Runout: Intersection of the thread cone and the pipe’s outside surface. The runout is the location on the outer surface where thread grooves vanish.

Scarf: The material removed from inside and outside surfaces of weld seam in resistance welded pipe. This material contains the oxides and metal that has been extruded from the weld seam during the welding process.

Seam annealing: The process by which the weld seam of electric welded pipe is heat treated after welding to a minimum of 1000 F or processed in such a manner that no untempered marensite remains.

Seam normalizing: The final heat treatment given to a pipe product that is produced from hot rolled skelp. The weld seam in this product is heated above the material’s transformation temperature (1650 F) and allowed to slow cool. The heated zone develops a microstructure that is typically found in a hot rolled or normalized steel product. This treatment eliminates hard brittle structures that can develop in the weld heat affected zone during the welding process.

Sizing: The mechanical forming of pipe by passing it through sets of rolls that rounds the pipe and gives the pipe its final outside diameter.

Spectrograph inspection: The process of determining the chemical makeup of a material using spectral (light) methods.

Stabbing: Guiding the end of a pipe into a coupling or tool joint when making a connection.

STC (Short Thread and Coupled): The description of an API casing connection that has an 8-round ( 8 threads per inch of length) thread with a modified V profile and a coupling made-up power-tight on one end of the pipe.

Steel Analysis: A term applied to the chemistry test results for a steel product.

Storage Compound: A substance that is applied to thread oil field pipe connections to protect against corrosion during shipment and/ or storage.

String (of pipe): The entire length of casing, tubing, or drill pipe run into a hole.

Tensile: In tensile testing, the ratio of maximum load to the original cross-sectional area, also called ultimate strength.

Tension setting depth: The term used to describe the depth to which a string of casing or tubing can be set based on the joint strength of the pipe located at the top of the string.

Thickness inspection: Inspection of the pipe wall by use of mechanical calipers, micrometers, etc., or by the use of ultrasonic compression waves.

Third Party inspection: Inspection performed by companies other than the manufacturer or end user.

Thread Compound (thread dope): A substance that is applied to threaded oil field pipe connections prior to makeup. It provides lubrication during assembly and disassembly, and aids in sealing against high internal and external pressures during service.

Thread inspection: The visual and dimensional examination of threads. The visual inspection is preformed to determine if the threads have corrosion pitting or mechanical damage, such as tears and chatter. Dimensional inspection includes the determination of the thread lead, taper, thread height, stand-off, and thread cone pitch diameter.

Through wall hardness inspection: A hardness survey performed on a cross-section of pipe wall. In general, hardness impressions are made near the outside and inside surfaces and at the center of the cross-section.

Torque: The turning force that is applied to a shaft or other rotary mechanism to cause it to rotate or tend to do so. Torque is measured in foot-pounds, joules, meter-kilograms, and so forth.

Transition range of Collapse: The collapse strength of pipe which falls within the range calculated using the Transition Collapse Pressure Formula specified in the American Petroleum Institute’s (API) Bulletin 5C3.

Transverse: Perpendicular to the direction of rolling.

Tubing joint strength: For non-upset tubing, the joint strength is the product of the specified minimum yield strength and the area of the section under the last perfect thread of the pipe. For upset tubing, the joint strength is the product of the specified minimum yield strength and the area of the pipe body.

Ultrasonic inspection: A nondestructive inspection method that uses high frequency sound waves to detect discontinuities in materials such as pipe.

Upsetting: The process of mechanically deforming the end of a piece of tubing with a punch and die to increase the wall thickness. Prior to upsetting, the end of the tube is heated to approximately 2300 F to promote flow of the material into the upsetting die. A punch is inserted into the bore of the tube to limit the flow of the material toward the inside of the tube during the upsetting operation. Upsetting is performed to increase the cross-section at the end of tubing so that a thread can be cut on the end of the tube.

UV: The abbreviation of ultraviolet. Ultraviolet is electromagnetic radiation (light) that has a wave length and frequency that puts it outside the visible light spectrum. Ultraviolet light can be seen using filters and phosphorescent materials. Magnetic particles and dye penetrate inspection processes have been developed that use ultraviolet light and phosphorescent materials to delineate surface imperfections in material.

Visual Inspection: An inspection process that uses the eye and adequate lighting with or without the aid of optics to examine the attributes of a product.

Wall: The thickness of a joint of pipe’s solid steel side. It is the difference between the inside diameter (ID) and the outside diameter (OD).

Weld line UT Inspection: The nondestructive inspection of the weld line in electric resistance welded pipe using the ultra sonic inspection process. It is used to ensure weld integrity.

Wellbore: A borehole; the hole drilled by the bit.

Yield: The first stress in a material, usually less than the maximum attainable stress at which an increase in strain occurs without an increase in stress. Yield strength is the stress at which a material exhibits a specified deviation from proportionality of stress and strain.